These notes apply to ImageJ 1.32 and later, which is distributed as a Windows installer. The notes for earlier versions distribued as a ZIP archive are available at rsb.info.nih.gov/ij/docs/install/windows2.html

Requirements
ImageJ requires Windows 95 or later. It runs on a machine with 64MB but it runs better with 256MB or more, particularly when working with large images and/or stacks.

Memory
Use the Edit/Options/Memory command to make more than 128MB available to ImageJ. Note that setting the "Maximum Memory" value to more than about 75% of real RAM may result in poor perfomance due to virtual memory "thrashing". The maximum amount of memory that can be allocated is about 1.7 GB.

With ImageJ 1.32 or later, use the Edit/Options/Memory command to make more than 192MB of memory available to ImageJ. Setting the "Maximum Memory" value to more than about 75% of real RAM may result in poor perfomance due to virtual memory "thrashing". The maximum amount of memory that can be allocated is about 1.8 GB.

Upgrading
To upgrade to the latest version of ImageJ, replace the ij.jar file in the ImageJ folder with a newer one from http://rsb.info.nih.gov/ij/upgrade/index.html.

Drag and Drop
The Windows version of ImageJ opens images, text files, ROIs and LUTs dropped on the title bar or menu bar of the "ImageJ" window. On Windows 2000/XP, it opens files dropped on the ImageJ shortcut, but another copy of ImageJ is launched if ImageJ is already running.

Known Problems

1. Java 1.4.2 crashes when running ImageJ. This bug has been reported to Sun and is fixed in the Java 1.5 beta.
2. ImageJ cannot use more than about 1.7GB of memory, regardless of how much RAM is installed.
3. With Java 1.5, Edit/Paste does not work correctly in the text editor. ImageJ 1.33k has a work around for the keyboard shortcut (Ctrl+V).
4. With Java 1.5, File/Print causes ImageJ to crash.
5. With Java 1.3.1, File/Print does not correctly print large line drawings (e.g., the plots generated by Analyze/Gels/Plot lanes).
6. The text cursor is sometimes used instead of the cross hair. As a work around, check "Use Pointer Cursor" in Edit/Options/Misc or change the Windows XP cursor scheme in Control Panel/Mouse/Pointers to "(None)".

Adding a JAR File
Some plugins require adding a JAR file to ImageJ. In ImageJ 1.31 or later, this is done by copying the JAR file into the plugins folder or an immediate subfolder of the plugins folder, then restarting ImageJ. To compile a plugin that uses a JAR file, copy the JAR file to the Java extensions folder, ImageJ\jre\lib\ext.

Using ImageJ with Java 1.5 (5.0)
Download the Windows version of ImageJ that is bundled with Java 1.5 (aka java 5.0) from rsb.info.nih.gov/ij/download.html.